U.S. patent number 4,681,567 [Application Number 06/847,757] was granted by the patent office on 1987-07-21 for syringe with safety sheath.
Invention is credited to Paul L. Ebaugh, Edwin J. Masters.
United States Patent |
4,681,567 |
Masters , et al. |
July 21, 1987 |
Syringe with safety sheath
Abstract
An improved syringe of the type comprising a barrel having a
needle extending from the lower end, the syringe further comprising
a knob extending outwardly from the barrel near the lower end, and
a sheath slideably mounted on the barrel and slideable between a
retracted position and an extended position. The sheath has a slot
for receiving the knob, the slot having tabs for releasably
retaining the sheath in its retracted position releasable upon
downward pressure applied to the sheath, and tabs for lockingly
engaging the knob to lock the sheath in the extended position.
Inventors: |
Masters; Edwin J. (Sikeston,
MO), Ebaugh; Paul L. (Cape Girardeau, MO) |
Family
ID: |
25301422 |
Appl.
No.: |
06/847,757 |
Filed: |
April 3, 1986 |
Current U.S.
Class: |
604/198 |
Current CPC
Class: |
A61M
5/3271 (20130101); A61M 2005/3247 (20130101) |
Current International
Class: |
A61M
5/32 (20060101); A61M 005/32 () |
Field of
Search: |
;604/198,197,192,263,187 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Yasko; John D.
Attorney, Agent or Firm: Rogers, Howell, Moore &
Haferkamp
Claims
What is claimed is:
1. An improved syringe of the type comprising a barrel having a
needle extending from the lower end, the improvement
comprising:
at least one knob extending outwardly from the barrel near the
lower end;
a sheath slideably mounted on the barrel and slideable between a
retracted position over the barrel in which the sheath does not
obstruct access to the needle and an extended position at least
partly over the needle in which the sheath obstructs access to the
needle;
at least one longitudinal slot means in the sheath for receiving
the knob, the slot means having means for releasably retaining the
sheath in its retracted position, said releasable retaining means
being releasable upon downward pressure applied to the sheath, the
slot means further having means for lockingly engaging the knob to
lockingly engage the sheath in the extended position.
2. The improved syringe of claim 1 wherein the slot means is an
open slot extending through the wall of the sheath, for receiving
the knob.
3. The improved syringe of claim 1 wherein the slot means is a
longitudinal groove in the interior of the sheath for receiving the
knob.
4. The improved syringe of claim 1 wherein the sheath has raised
ribs at the upper end to aid in gripping the sheath.
5. The improved syringe of claim 1 wherein there are two knobs
extending from the barrel at diametrically opposed locations, and
wherein there are two slot means in the sheath, each slot means
receiving one of the knobs.
6. The improved syringe of claim 2 wherein the knob is triangularly
shaped, with one of the vertices oriented upwardly.
7. The improved syringe of claim 2 wherein the knob and the sheath
have radially inwardly and outwardly beveled faces, respectively,
that engage each other to retain the sheath against the barrel.
8. The improved syringe of claim 2 wherein the slot means extends
upwardly from the lower end, the slot means having a first set of
opposing tabs extending into the slot means near the lower end, the
first set of tabs engaging the knob when the sheath is in the
retracted position and releasably retaining the sheath in the
retracted position, the first set of tabs having angled lower
faces, these angled lower faces forcing the tabs apart to clear the
knob when forced downwardly against the knob; the slot further
having a second set of opposing tabs extending into the slot above
the first set of tabs, near the upper end of the slot, the second
set of tabs having angled lower faces and flat upper faces that
form a shoulder, these angled lower faces forcing the tabs apart to
clear the knob when forced against the knob, the second set of tabs
resiliently snapping back after clearing the knob, the shoulders
and the upper end of the slot cooperating to trap the knob and lock
the sheath in the extended position.
9. The improved syringe of claim 8 wherein the lower faces of the
first set of tabs are beveled to face radially outwardly and
wherein the knob has faces beveled to face inwardly, the beveled
faces on the knob engaging the beveled faces of the tab and
retaining the sheath against the barrel.
10. An improved syringe of the type comprising a barrel having a
needle extending from the lower end, the improvement
comprising:
at least one knob extending outwardly from the barrel near the
lower end;
a sheath slideably mounted on the barrel and slideable between a
retracted position over the barrel in which the sheath does not
obstruct access to the needle and an extended position at least
partly over the needle in which the sheath obstructs access to the
needle;
at least one longitudinal slot in the sheath for receiving the
knob, the slot having a first set of opposing tabs extending into
the slot, the first set of tabs engaging the knob when the sheath
is in the retracted position and releasably retaining the sheath in
the retracted position, the first set of tabs having angled lower
faces, these angled lower faces forcing the tabs apart to clear the
knob when forced downwardly against the knob; the slot further
having a second set of opposing tabs extending into the slot above
the first set of tabs, the second set of tabs having angled lower
faces and flat upper faces that form a shoulder, these angled lower
faces forcing the tabs apart to clear the knob when forced against
the knob, the second set of tabs resiliently snapping back after
clearing the knob, the shoulders preventing upward movement of the
sheath and locking the sheath in the extended position.
11. The improved syringe of claim 10 wherein the sheath has raised
ribs at the upper end to aid in gripping the sheath.
12. The improved syringe of claim 10 wherein there are two knobs
extending from the barrel at diametrically opposed locations, and
wherein there are two slots in the sheath, each slot receiving one
of the knobs.
13. The improved syringe of claim 10 wherein the knob is
triangularly shaped, with one of the vertices oriented
upwardly.
14. The improved syringe of claim 10 wherein the knob and the
sheath have radially inwardly and outwardly beveled faces,
respectively, that engage each other to retain the sheath against
the barrel.
15. The improved syringe of claim 14 wherein the lower faces of the
first set of tabs are beveled to face radially outwardly and
wherein the knob has faces beveled to face inwardly, the beveled
faces on the knob engaging the beveled faces of the tab and
retaining the sheath against the barrel.
16. An improved syringe of the type comprising a barrel having a
needle extending from the lower end, the improvement
comprising:
at least one knob extending outwardly from the barrel near the
lower end, the knob having a generally triangular shape with one of
the vertices oriented upwardly, and two of the faces of the
triangle facing obliquely upwardly, the two upwardly facing faces
being beveled to face generally radially inwardly;
a sheath slideably mounted on the barrel and slideable between a
retracted position over the barrel in which the sheath does not
obstruct access to the needle and an extended position at least
partly over the needle in which the sheath obstructs access to the
needle;
at least one longitudinal slot extending upwardly from the lower
edge of the sheath for receiving the knob, the slot having a first
set of opposing tabs extending into the slot, the first set of tabs
engaging the knob when the sheath is in its retracted position and
releasably retaining the sheath in its retracted position, the
first set of tabs having angled lower faces, these angled lower
faces forcing the tabs apart to clear the knob when forced
downwardly against the knob, the lower faces of the first set of
tabs further being beveled to face generally radially outwardly,
the beveled faces on the knob engaging these beveled faces on the
first set of tabs and retaining the sheath against the barrel; the
slot further having a second set of opposing tabs extending into
the slot above the first set of tabs, near the upper end of the
slot, the second set of tabs having angled lower faces and flat
upper faces that form a shoulder, these angled lower faces forcing
the tabs apart to clear the knob when forced against the knob, the
second set of tabs resiliently snapping back after clearing the
knob, the shoulders and the end of the slot cooperating to trap the
knob and lock the sheath in the extended position.
17. The improved syringe of claim 16 wherein the sheath has raised
ribs at the upper end to aid in gripping the sheath.
18. The improved syringe of claim 16 wherein there are two knobs
extending the barrel at diametrically opposed locations, and
wherein there are two slots in the sheath, each slot receiving one
of the knobs.
19. An improved syringe of the type comprising a barrel having a
needle extending from the lower end, the improvement
comprising:
at least one knob extending outwardly from the barrel near the
lower end;
a sheath slideably mounted on the barrel and slideable between a
retracted position over the barrel in which the sheath does not
obstruct access to the needle and an extended position at least
partly over the needle in which the sheath obstructs access to the
needle;
at least one longitudinal groove in the interior of the sheath for
receiving the knob, the groove having first means for engaging the
knob when the sheath is in the retracted position to retain the
sheath in its retracted position; means for releasing the
engagement between the first engaging means and the knob upon
downward pressure applied to the sheath; and second means for
engaging the knob when the sheath is in its extended position to
lock the sheath in the extended position.
20. The improved syringe of claim 19 wherein the means for
releasing the engagement between the first engaging means and the
knob comprises a sloped surface on at least one of the tab or the
first engaging means.
21. The improved syringe of claim 19 wherein the second means for
engaging the knob comprises a means for defining a shoulder
generally perpendicular to the groove and means on the knob for
engaging the shoulder.
22. The improved syringe of claim 19 wherein the knob has a sloped
upper face; and wherein the first engaging means comprises a tab
extending from the bottom of the groove into the groove near the
lower end.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
This invention relates to improvements in syringes and in
particular to a syringe having a safety sheath for preventing
needlesticks.
Hypodermic needles, for example those used for injections or for
taking blood samples, are usually equipped with a removeable cap
that protects and helps keep the needle sterile. The cap is usually
replaceable to cover the used, contaminated needle and prevent
accidental needlesticks. However, accidental needlesticks during
recapping have long been a problem. Because of tension, time
pressure, or fatigue, needlesticks during recapping occur with
alarming frequency despite frequent warnings to be careful, and
they account for the majority of accidental needlesticks.
Eliminating recapping will not solve the problem because the
uncapped needle is so dangerous. Indeed, a large number of
accidental needlesticks are caused by uncapped needles found in
beds, on floors, or in garbage cans. Even where there is a no
recapping policy, the needles are often recapped because of these
dangers.
Accidental needlesticks are serious because they can spread
diseases, including hepatitis, venereal diseases, and of most
recent concern: AIDS. A needlestick causes fear and anxiety in the
victim. Both the victim and the patient may be subjected to a
battery of expensive, time-consuming tests. Accidental needlesticks
during recapping can cost even a relatively small health care
institution thousands of dollars annually. Even worse than the
economic cost, however, is the transmission of disease.
For example, the victim of a needlestick from a needle contaminated
by an AIDS patient must be repetitively tested for several months
after the accident. It is documented that after such a needlestick,
the victim may test positive for exposure to the AIDS virus, even
if the disease is not contracted. A positive test would cause great
fear and anxiety in the victim, would seriously disrupt the
victim's personal life, and might even end the victim's ability to
work in health care.
Despite the very serious nature of the problem, and the severity of
the consequences, the problem of accidental needlesticks has
persisted for many years without any satisfactory solution. One
approach to a solution is to modify the cap. For example, a recent
article Sumner, "Needlecaps to Prevent Needlestick Injuries",
INFECTION CONTROL (1985) Vol. 6, No. 12, p. 495, discusses the
needlestick problem and discloses a needlecap with a small, wide
angle funnel surrounding the cap opening. This funnel acts as both
a guide and a shield. However, improvements to the cap do not
totally eliminate the possibility of needlesticks. The action of
bringing the cap and needle together still poses the threat of an
accidental needlestick.
Another approach to a solution is to provide a sheath that can be
slid down over the needle from behind, eliminating the risky action
of bringing the cap and needle together. There have been several
syringe constructions having sheaths that can be slid down over the
needle. Bastien, U.S. Pat. No. 2,571,653 discloses a Syringe having
a sheath slideably mounted over the barrel to hide the needle from
view. The sheath has a V-shaped latch that can engage grooves in
the barrel of the syringe. This is not a safety device, but merely
a device to hide the needle from the patient; the sheath is
designed to be freely moveable to expose the needle. Wulff, U.S.
Pat. No. 3,780,734 discloses a Hypodermic Syringe Holder and
Injector Device having a slideably mounted guard. This is not a
syringe but a syringe holder, and is designed for veterinary use.
The device would be cumbersome to use and difficult and expensive
to make. When the used syringe is removed from the device, the
needle will be exposed. Leeson et al., U.S. Pat. No. 3,890,971
discloses a Safety Syringe having a lockable plunger and a
lockable, slideable needle cap. The device is very complex and
would be difficult and expensive to make. Sampson et al., U.S. Pat.
No. 4,425,120, discloses a Shielded Hypodermic Syringe having a
needle guard mounted on the syringe barrel for movement between an
extended position shielding the needle and a retracted position.
The guard is lockable in each position with tracks on the inside of
the guard and track engaging members on the barrel. This device
would be difficult to operate because the tracks must be aligned
with the track engaging members, and it requires a twisting motion
to lock and unlock the needle guard. The device would also be
difficult and expensive to make.
The inventors have developed a syringe with a safety sheath that
eliminates the need for recapping the syringe after use. The sheath
is slideably mounted over the barrel of the syringe and after use
is simply slid downwardly to its extended position over the needle
until it locks, thereby shielding the needle. The syringe has at
least one knob projecting outwardly from the barrel. The sheath
also has at least one longitudinal slot for receiving the knob. The
slot has a first set of opposing tabs projecting into the slot, the
lower faces of which engage the top of the knob to retain the
sheath in its retracted position. The lower faces of the first set
of tabs are angled. These angled lower faces force the tabs apart
to clear the knob when the sheath is forced downwardly against the
knob. The slot also has a second set of opposing tabs projecting
into the slot above the first set. The second set of tabs have
angled lower faces and flat upper faces that form a shoulder. The
angled lower faces force the tabs apart to clear the knob when the
sheath is forced downwardly against the knob. The tabs resiliently
snap back after clearing the knob, and the shoulders formed by the
upper faces of the tabs engage the bottom surface of the knob and
lock the sheath in the extended position.
The syringe of the present invention has a safety sheath that is
retained in its retracted position until positive force is applied
to overcome the resistance of the first set of tabs. The sheath is
easily operated to its extended position by simply pushing the
sheath downward. The sheath is easily locked in its extended
position by simply pushing the sheath all the way down until the
second set of tabs engage the knob. This positive locking action
requires no special alignment or manipulation. The locking is
positive and easy to visually confirm.
The syringe of the present invention is of simple construction and
will be easy and inexpensive to make and simple to use. The locking
action is positive and visually confirmable, and without any
special manipulation that can be improperly done. The syringe can
thus be widely used to eliminate the dangers of needlesticks during
recapping.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation view of a first embodiment of a syringe
with a safety sheath constructed according to the principles of
this invention, with the safety sheath in the retracted
position;
FIG. 2 is a side elevation view of the syringe with the safety
sheath in the extended position;
FIG. 3 is a bottom end view of the syringe as it is shown in FIG.
1;
FIG. 4 is a partial side elevation view of the barrel of the
syringe with the safety sheath removed, showing a knob;
FIG. 5 is a partial side elevation view of the barrel of the
syringe with the safety sheath removed, showing the knobs in
profile;
FIG. 6 is a side elevation view of the safety sheath with a portion
broken away to show the interior;
FIG. 7 is a partial cross-sectional view of the syringe taken along
the plane of line 7--7 in FIG. 1, showing the engagement between
the knob and the safety sheath;
FIG. 8 is a side elevation view of a second embodiment of a syringe
with a safety sheath constructed according to the principles of
this invention, with the safety sheath in the retracted
position;
FIG. 9 is a second side elevation view of the syringe turned to
show the tunnel in the safety sheath for receiving the knob on the
syringe barrel;
FIG. 10 is a side elevation view of the syringe with the safety
sheath in the extended position;
FIG. 11 is a partial cross-sectional view of the syringe taken
along the plane of line 11--11 in FIG. 10, showing the engagement
between the knob and the safety sheath in the extended
position;
FIG. 12 is a partial perspective view of the lower end of the
safety sheath;
FIG. 13 is a cross-sectional view of the safety sheath taken along
the plane of line 13--13 in FIG. 12; and,
FIG. 14 is a partial perspective view of the lower end of the
syringe showing the knob on the barrel.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A first embodiment of a syringe with a safety sheath constructed
according to the principles of this invention is indicated
generally as 20 in FIGS. 1 and 2. The syringe 20 comprises a barrel
portion 22 terminating in a tip 24 at the lower end. Gradations or
indicia (not shown) may be provided on the barrel 22 to indicate
the volume in the syringe 20. A hypodermic needle 26 is mounted to
the tip 24. Two diametrically opposed fingergrips 28 project
radially outwardly from the top of the barrel 22. A plunger 30
reciprocates in the barrel 22 to draw and expel substances in the
barrel 22.
At least one knob 32 projects radially outwardly near the bottom of
the barrel 22. There are preferably two diametrically opposed
knobs, as best shown in FIGS. 3 and 5. As shown in FIGS. 1-3, knobs
32 are preferably triangularly shaped with one of the vertices
pointed upwardly. The upwardly facing left and right sides 34 and
36 of the knobs 32 are beveled to face radially inwardly, as best
shown in FIGS. 3 and 7. The downwardly facing side 38 of the knob
32 extends generally horizontally, perpendicular to the axis of the
syringe 20.
A sheath 40 is mounted on the barrel 22. The sheath 40 is
preferably made of a resilient, transparent plastic so it does not
mask the gradations or indicia on the barrel 22. The sheath 40 is
slideable between a retracted position, shown in FIG. 1, and an
extended position, shown in FIG. 2. The sheath 40 has a slot 42 to
receive each knob 32 on the barrel 22. Thus, in the preferred
embodiment there are two diametrically opposed slots 42 in the
sheath 40 to accommodate the two knobs 32. The slots 42 extend
upwardly from the bottom edge of the sheath 40. The slots 42
preferably extend through the thickness of the sheath 40. However,
as discussed below, slot 42 could be replaced with a groove on the
inside side of the sheath 40, in which case the sets of tabs
hereinafter described might be replaced with some other means for
engaging the knob 32.
A first pair of tabs 44 extend from opposite sides into each slot
42, near the lower end. The lower edges 46 of tabs 44 are angled
downwardly and are also beveled to face radially outwardly. The
central section 48 of slot 42 has generally parallel sides, and is
sized to accommodate knob 32. A second pair of tabs 50 extend from
opposite sides into slot 42, above the first pair of tabs 44 near
the upper end of the slot 42. The lower edges 52 of the tabs 50 are
angled downwardly, and the upper edges 54 of the tabs 50 extend
generally horizontally to form shoulders perpendicular to the slot
42.
In the first preferred embodiment, a plurality of raised annular
ribs 56 extend around the sheath 40 near the top to provide a grip
to slide the sheath 40 relative to the barrel 22.
In FIG. 1, sheath 40 is in its retracted position. As shown in FIG.
7, the inwardly beveled sides 34 and 36 of the knobs 32 engage the
outwardly beveled edges 46 of the tabs 44, to retain the sheath 40
against the barrel 22. The engagement between the lower edges 46 of
the tabs 44 and the edges 34 and 36 of knob 32 helps to retain the
sheath 40 in the retracted position. However, the angled edges 46
of the tabs 44 force the tabs 44 apart when sheath 40 is forced
against the knob 32. The resiliency of the material that the sheath
40 is constructed from, and the presence of slots 42, permit the
sheath 40 to flex sufficiently for the tabs 44 to clear the knob
32.
After tabs 44 clear the knob 32, the sheath 40 slides freely
downwardly until the tabs 50 engage knob 32. The engagement between
the tabs 50 and the knobs 32 resists further downward movement of
the sheath 40. However, the angled lower edges 52 of the tabs 50
force the tabs 50 when sheath 40 is forced against the knob 32.
Again, the resiliency of the material and the presence of slots 42
permit the sheath 40 to flex sufficiently for tabs 50 to clear the
knob 32. After tabs 50 clear the knob 32, they resiliently snap
back together, and the shoulders formed by upper edges 54 of the
tabs 50 engage the bottom side 38 of the knob 32 to lock sheath 40
in its extended position. Thus locked, sheath 40 cannot move upward
from its extended position, and sheath 40 blocks access to needle
26, preventing an accidental needlestick.
A second embodiment of a syringe with a safety sheath constructed
according to the principles of this invention is indicated
generally as 100 in FIGS. 8-10. Like syringe 20, syringe 100
comprises a barrel portion 102 terminating in a tip 104 at the
lower end. Gradations or indicia (not shown) may be provided on the
barrel 102 to indicate the volume in the syringe 100. A hypodermic
needle 106 is mounted to the tip 104. Two diametrically opposed
fingergrips 108 project radially outwardly from the top of the
barrel 102. A plunger 110 reciprocates in the barrel 102 to draw
and expel substances in barrel 102.
At least one knob 112 projects radially outwardly near the bottom
of the barrel 102. As shown in FIGS. 11 and 14, in the preferred
embodiment, knob 112 has an upwardly facing, upper face 114 that
slopes radially outwardly in the downward direction. Knob 112 also
has a downwardly facing, lower face 116, that is preferably
perpendicular to the axis of the syringe 100.
A sheath 118, like sheath 40, is mounted on the barrel 102. The
sheath 118 is preferably made of a resilient, transparent plastic
so that it does not mask the gradations or indicia on the barrel
102. The sheath 118 is slideable between a retracted position,
shown in FIGS. 8 and 9, and an extended position, shown in FIG. 10.
The sheath 118 has a slot or groove 120 in its interior surface
which, unlike the slot 42 in sheath 40, does not extend all the way
through the wall of sheath 118. Thus, as best shown in FIGS. 8, 11,
12 and 13, groove 120 forms a tunnel 122 for receiving the knob 112
on the barrel 102.
As best shown in FIG. 11, first tab 124 extends from the bottom
into the groove 120 near the lower end of the sheath 118. Tab 124
releasably engages the upper face 114 of the knob 112 when the
sheath 118 is in its retracted position. This engagement helps to
retain the sheath in its retracted position. The sloped face 114 of
knob 112 forces the tab 124 outwardly when sheath 118 is forced
downwardly. The resiliency of the material that sheath 118 is made
from permits the sheath 118 to flex sufficiently for the tab 124 to
clear the knob 112. Instead of tab 124, some other means for
releasably engaging the knob 112 may be provided, for example a
constriction in groove 120 or tabs extending from the sides of
groove 120.
The central section 126 of groove 120 is sized to accommodate knob
112, and allow the sheath 118 to slide freely downwardly over knob
112.
A second tab 128 extends from the bottom into the groove 120, above
tab 124 near the upper end of groove 120. As shown in the Figures,
tab 128 can be formed by a constriction in tunnel 122. Tab 128 has
a sloped lower face 130, and a flat upper face 132 generally
perpendicular to the axis of the groove 120 to form a shoulder. The
sloped lower face 130 of tab 128 releasably engages the upper face
114 of the knob 112. The sloped face 114 of knob 112 forces the tab
128 outwardly when sheath 118 is forced downwardly. Again, the
resiliency of the material permits the sheath 118 to flex
sufficiently for tab 128 to clear knob 112. After tab 128 clears
the knob 112, it resiliently snaps back, and the shoulder formed by
the upper face 132 of tab 128 engages the bottom face 116 of knob
112 to lock the sheath 118 in its extended position.
In the second preferred embodiment, a plurality of raised annular
ribs 134 extend around the sheath 118 near the top to provide a
grip to slide the sheath 118 relative to the barrel 102.
OPERATION
The syringe 20 of the first preferred embodiment may be provided
with the sheath 40 in its retracted position as shown in FIG. 1.
The syringe 20 may have a removeable cap (not shown) to help
protect the needle 26 and keep it sterile. The cap is removed and
syringe 20 can be used, for example to give an injection. After
use, the contaminated needle 26 is not recapped. Instead, the
sheath 40 is grasped by the raised ribs 56, and urged downwardly.
The downward force applied to the sheath 40 urges the tabs 44
against the knob 32. The angled edges 46 of the tabs 44 force the
tabs 44 apart to clear the knob 32. Once the tabs 44 clear the knob
32, the sheath 40 slides freely downwardly until the tabs 50 engage
the knob 32. Continued downward pressure forces the tabs 50 against
the knob 32. The angled lower edges 52 of the tabs 50 force the
tabs 50 apart to clear knob 32. Once the tabs 50 clear the knob 32,
the tabs snap resiliently back, locking the sheath 40 in its
extended position. The shoulders formed by the top edges 54 of the
tabs 50 engage the bottom side 38 of the knob 32, preventing the
sheath 40 from moving upward.
The syringe 100 of the second preferred embodiment may be provided
with the sheath 118 in its retracted position. The syringe 100 may
have a removable cap (not shown) to help protect the needle 106 and
keep it sterile. The cap is removed and syringe 100 can be used.
After use, the contaminated needle 106 is not recapped. Instead,
the sheath 118 is grasped and urged downwardly. The downward force
applied to sheath 118 urges the tab 124 against the knob 112. The
sloped upper face 114 of knob 112 forces tab 124 outwardly to clear
knob 112. Once tab 124 clears the knob 112, the sheath 118 slides
freely downwardly until the tab 128 engages knob 112. Continued
downward pressure forces the tab 128 against knob 112. The sloped
upper face 114 of the knob 112 forces tab 128 outwardly to clear
knob 112. Once the tab 128 clears the knob 112, the tab snaps
resiliently back, locking the sheath 118 in its extended position.
The shoulder formed by the top face 132 of tab 128 engages the
bottom face 116 of knob 112, preventing the sheath 118 from moving
upwardly.
In either embodiment, in a simple, downward motion the needle is
covered. The positive snap action and visual confirmation ensure
that the sheath 40 is properly locked. The motion of bringing the
needle and cap together is eliminated; the point of the needle is
never directed toward the user and thus the potential for
accidental needlestick is reduced.
There are various changes and modifications which may be made to
the invention as would be apparent to those skilled in the art.
However, these changes or modifications are included in the
teaching of the disclosure, and it is intended that the invention
be limited only by the scope of the claims appended hereto.
* * * * *